Data concerning the chemical and physical properties of the carcinogenic N-nitroso compounds will be collected. Specific emphases will include studies of: a) catalysis of N-nitrosation reactions of environmental interest by metal species; b) mechanisms of microsomal attack on the dialkylnitrosamines, with comparison of results to in vivo metabolic data; c) preparation of novel nitrosamines and their derivatives for chemical and biological studies. Possible implications of this work with respect to the overall goal of human cancer prevention will be considered.